I think based on the original reports an OD was a no-brainer.
I'd say he OD'ed on too much iron in his forehead.
I think that makes a lot more sense than him getting brained by a club-wielding wife, which is what I initially thought when the story was reported. I looked at those SUV pictures closely today, and I can't see any other marks on the car from a club, other than the two broken windows, which seems unlikely if his wife was in some kind of SUV attacking rage.
I'm not saying that they didn't have a big fight, possibly even a physical fight, but it seems clear now that his problems were more drug/alcohol related, than injury related (either car or wife injury).
It's also clear that the police covered for him initially, especially if reports are true that his wife handed the EMTs Vicodin and Ambien bottles before they transported Tiger to the hospital. That alone would have been "reasonable cause" to draw Tigers blood at the hospital, even without a warrant.